The quality of your sleep, along with your bedtime and wake time, influence your body fat composition.

You already know that it’s important to get a solid night of sleep on a regular basis. For the vast majority of people, the "sweet spot" for the right amount of sleep per night is between 6 and 9 hours.

When we don't sleep enough, two hormones in our body are greatly affected: ghrelin and leptin. Ghrelin is a hormone that gives us the "go" signal, meaning that we are hungry and need to eat. On the other end is leptin, a hormone that signals satiety and tells us to stop eating. When we don't get enough sleep, even after just a few short nights of less slumber, the balance between ghrelin and leptin is tipped. We have more ghrelin and less leptin. As a result, the signal that tells us we're full becomes weak, and the "you're hungry, eat!" signal is strengthened.

Researchers at BYU investigated over 300 college-aged women over the course of a few weeks, assessing them for body fat composition and keeping track of their sleep patterns for one week. Results showed that participants who obtained less than 6.5 or more than 8.5 hours of sleep per night had higher body fat.

What is novel in this study is their look at the timing of sleep and its impact on body fat composition. The researchers found that a consistent bedtime and, more importantly, wake time, were related to lower body fat. Participants who had more than 90 minutes of variation in their sleep/wake times were more likely to have higher body fat composition than those with less than 60 minutes of variation.

We are all born with internal clocks called circadian rhythms. These rhythms are on a roughly 24-hour clock and keep our bodies in check throughout the day. Not only do circadian rhythms impact our sleep schedules, but they also govern many other complex functions in our body—notably, when hormones are released by various organs in our body. Keeping a fixed wake time seven days per week helps to keep the circadian clock in check all day long. Even though staying with the same bedtime is important, having a constant wake time has many more implications in keeping our body's physiology on the right clock. Plus, not sleeping in allows for us to be out of bed and active for more hours, which helps with lowering body fat.

Finally, the researchers also noted that sleep quality greatly impacted body composition. Participants who slept better had less body fat. A myriad of reasons can factor into why sleep quality might be disrupted: pain, sleep apnea, anxiety, depression, fibromyalgia, etc. And the more disrupted one's sleep is, the more likely they aren't getting all of the benefits of a solid night's sleep. What’s more, less human growth hormone is produced and more of the stress horomone cortisol is released (leading one's body to feel more stressed). These are all things that can impact leptin and ghrelin production, thereby increasing body fat composition.

If you find that you're having trouble logging enough sleep, getting quality sleep or keeping to a sleep schedule, consider seeing a sleep specialist to help assess any issues that might be contributing to your insomnia. Also, check out this column for more ideas on how to treat insomnia naturally and get both your sleep and weight on the right track for 2014.

Popular Tags

We're Beauty, Evolved

Beautiful is a feeling. It’s presence of mind, a strong body, a glow from the inside out. It's being comfortable in your own skin. It's a lifestyle. Our mission is to make beauty your lifestyle, through quizzes, articles and personalized advice backed by science. We know you're busy, so no fluff. Just cutting edge, well-researched info to help you be healthy, harmonious and beautiful.